The invention relates to a changeable pressure-tight process window unit for the optically spectroscopic study of pipelines or apparatus through which products flow.
DE 4 414 975 A1 describes a device for the spectroscopic analysis of process mixtures, whose main component is a measurement crystal which is immersed in the process space and which is arranged below two conically profiled process windows for the input and output of measurement radiation. In this case, the windows are arranged in such a way that the cone diameter widens towards the apparatus interior side in order, when operating under high pressure, to obtain a self-sealing barrier for the process mixture in the reactor interior after a break of the measurement crystal. The use of adhesives for the process windows mentioned in DE 4 414 975 A1 is also proposed.
It is an object of the invention to develop an improved process window unit which, on the one hand, can be fitted pressure-tightly on a container or a pipeline and, on the other hand, can be rapidly installed and removed for cleaning and monitoring purposes.
The object is achieved according to the invention by a process window unit comprised of a window frame for holding a window, a screw cylinder with a radiation passage in its core and an external thread for screwing the screw cylinder into the window frame, the window frame having a complementary internal thread, and an elastic seal between the window and the screw cylinder, wherein the window is designed with a conically tapering profile on the process side opposite the screw cylinder. That is to say, the window is conically tapered away from the screw cylinder.
In a preferred embodiment, the process window unit has an additional seal above the thread of the screw cylinder, between the screw cylinder and the window frame.
The fastening of the process window unit to the container or pipeline is particularly advantageously carried out by means of a clamp-ring screw connection, which is fastened to the pipeline or the container, in particular releasably. The clamp ring of the clamp-ring screw connection is designed conically narrowed downwards, and it is pressed into the seal seat of the screw connection with the aid of a union nut on the screw connection, in such a way in that its inner face bears with a force-fit on the outer face of the screw cylinder. The process window unit, as an insert in the clamp-ring screw connection, can easily be removed from the pipeline or the process container, by removing the union nut and withdrawing the process window unit.
As an alternative to the clamp-ring screw connection, a second external thread may be fitted on the outer diameter of the screw cylinder, with the aid of which the process window unit can be screwed directly into an opening in the pipeline wall having a complementary internal thread. In this case, further ring seals are provided below the second external thread in the screw cylinder, i.e., disposed on said screw cylinder to enter said opening in advance of said second external thread, in order to seal the connection between the screw cylinder and the opening in the pipeline wall.
The process window unit permits, for example, inline measurement on any pipelines or reaction containers through which products flow. Optionally, the process window unit may also be fitted on a separable pipeline flange. Preferably, in particular for spectroscopic irradiation measurements, an arrangement is selected in which two process window units according to the invention are fitted opposite each other in a pipeline or a container.
The seals may be formed from known materials in accordance the requirements of the respective process in which they are to be used. Such materials include, for example, polytetrafluoroethylene (PTFE), Kalrez, (per fluoroelastomer) Viton Vinylidenfluorid hexafluoropropylene copolymerisate or at higher extreme temperatures and extreme pressure, Helicoflex rings may be used. For the clamp-ring screw connection, commercially available screw connections with standardized internal diameter may be used, to which the screw cylinder is optionally matched in terms of its external diameter.
For the mechanical parts of the process window which come into contact with product, the usual materials, such as stainless steel, possibly tantalum, Hastelloy(trademark) nickel-based alloy, or even polyvinyl difluoride (PVDF)xe2x80x94may be suitable. The optical parts, i.e., the windows, may be formed of the usual optical materials sapphire, glass, quartz glass, transparent plastic and the like.